Why won't your boiler turn off? Here we detail some common causes and potential solutions.
If you are facing the unsettling problem of a boiler that just won’t shut off, it’s one of those unexpected issues that can cause a lot of worry, but don’t panic – you’ve landed in the right spot.
In this troubleshooting guide, we’ll explore the most common reasons why your boiler might be running non-stop and, more importantly, what steps you can take to fix it.
Ready to unravel this boiler mystery? Let’s dive in!
PS - we fit new combi boilers with gas safe installation nationwide. Simply answer these questions, get your fixed price and you could get it installed as quick as tomorrow.
Why Won’t My Boiler Turn Off?
Note: For details on how to fix these issues (where safe for a DIYer), skip to the next section.
There may not be a single answer to this question.
After all, a boiler is a complex machine that features a range of components that could lead to a boiler staying on.
Let’s look at several potential explanations.
Again, please note that one or more of the causes discussed below might explain why your boiler isn’t turning off.
Faulty Programmer
First and foremost, there may be an issue with your boiler timer/heating programmer.
Also, just to note, if you have a boiler timer, this would turn your boiler on at a set time each.
However, a heating programmer would provide you with far more control over your boiler with modern integrated technology.
Either way, if your boiler timer or heating programmer develops a fault, this can nullify the instructions you’ve already set and may ultimately lead to your boiler staying on non-stop.
If you have a combi boiler, a single-channel programmer may be to blame, while for those with a regular boiler, it’s probably due to a two-channel programmer.
Issues With Your Thermostat
Another common reason why a boiler won’t turn off is that the thermostat is faulty.
Boiler thermostats are used to detect the water temperature in the pipework.
Once the temperature drops below a certain level, the thermostat will signal the boiler to heat up the water.
Of course, if your thermostat is faulty, it will not be able to tell when the boiler should turn on or off.
This could ultimately lead to your boiler failing to turn off when it should.
Faulty Valves
Boiler valves come with a range of switches to regulate the boiler and its pump.
When the valve opens, the switch becomes activated which is required to turn your boiler on. This means that it will begin to heat up water.
However, if the valve becomes faulty, the switch or switches can stay open (i.e., remaining in an on position).
This can happen if the valve itself is closed. Ultimately, this can result in your boiler or/and pump staying on.
Alternatively, the check valves or diverter valves may end up jamming or otherwise experiencing damage.
This can lead to hot water backflows and result in hot water continuing to flow through your heating system even when you switch off your boiler.
Wiring Issue
Last but not least, a wiring-related problem could also lead to a boiler staying on continuously.
Faulty wiring can easily result in false signals being sent throughout your boiler or alternatively, it may prevent the correct signals from reaching your boiler (e.g., the wiring between your PCB and boiler ignition may not be functioning correctly).
You may be interested in Gas Engineer Allen Hart explaining the most common boiler problems and how you can resolve them in the video below:
How to Fix the F1 Fault
Can I Fix a Boiler That Won’t Turn Off by Myself?
Note: If you have any reason to be concerned about your immediate safety (e.g., your boiler may be overheating), evacuate your property right away.
Then call 0800 111 999 for the gas emergency services if you are based in England, Scotland or Wales.
However, if you live in Northern Ireland, you want to call 0800 002 001.
Whether or not you’ll be able to fix this issue DIY will depend on the cause. If in doubt, consult a professional.
In this section, we’ll explore different fixes, whether or not they are DIY friendly, and what you can do in an effort to fix the problem where there are potential DIY solutions.
Please be aware that you should never undertake work on a boiler or heating system unless it is DIY-friendly.
Getting things wrong with work that is unsuitable for a DIYer could prove incredibly dangerous (e.g., resulting in gas leaks).
Moreover, along with being unsafe, attempting such work where it is unsuitable would also be against the law. In other words, certain jobs must be done by a Gas Safe Register engineer.
Faulty Programmer
DIY-Friendly? Yes
If you suspect that your boiler timer/heating programmer is faulty, this may be something you can fix by yourself.
Generally, simply resetting the timer/programmer should fix the problem.
To achieve this, all you will need to do is turn your boiler off and wait approximately half a minute before turning your boiler on again.
However, if in doubt, check the timer/programmer manual and follow the instructions. If your efforts fail, consult a qualified heating engineer.
Ultimately, resetting the timer/programmer should work if there is a minor problem whereas if there is a more extensive issue (or another issue at play entirely), these efforts will probably not suffice.
Issues With Your Thermostat
DIY-Friendly? Yes
If you think there’s an issue with your thermostat, there are steps you can take in an attempt to fix it DIY.
First, try turning down the temperature levels of your room thermostat.
If this works as intended, it should lower temperatures and ultimately cause your boiler to turn off.
Alternatively, you could attempt resetting the thermostat by turning it off and back on again.
If all else fails, we suggest checking whether the batteries need replacing. If the batteries are weak then a simple replacement should solve the issue.
If this succeeds, your thermostat should resume functioning as normal, allowing you to turn off your boiler.
However, if none of the potential solutions described here works, then you’ll need to hire a Gas Safe Register engineer.
Faulty Valves
DIY-Friendly? No
Unfortunately, you cannot adjust or attempt to fix faulty valves by yourself. This work must be left to a professional.
A qualified heating engineer will be able to inspect these components safely and make the necessary adjustments to fix your boiler.
Wiring Issues
DIY-Friendly? No
Again, just as you cannot fix faulty valves by yourself, wiring issues must also be solved by a professional.
Cost of Hiring a Heating Engineer to Fix a Boiler That Won’t Turn Off
The average labour cost of hiring a qualified heating engineer is around £30 to £60 per hour.
With that being said, the exact cost would depend on a range of factors such as your location.
The reason that location is considered a cost factor is that heating engineers charge different rates across the UK.
Here are the costs of specific repairs/replacement jobs to fix a boiler that won’t switch off:
Fix a faulty timer/programmer - £30 to £120
Replace a timer/programmer - £15 to £30
Fix a faulty thermostat - £30 to £120
Replace a thermostat - £50 to £200
Fix faulty valves - £30 to £120
Solve wiring issues - £30 to £180
Replace an entire boiler * - £800 to £2,800
*The reason we’ve included replacing an entire boiler is that in some instances (especially where a boiler is old or/and beyond economic repair), it can be more financially sensible to simply have a new boiler installed.
Of course, given the cost of replacing a boiler, you may be reluctant to consider this option (or it may seem outright impossible in the current economic climate).
However, if the upfront cost is a big issue, you might want to consider the option of purchasing a boiler on finance. This would generally involve paying interest, although zero-interest packages do exist.
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